1. Field of the Invention
The present invention relates to an irrigation control valve and an irrigation system having a liquid supply tube and a plurality of identical irrigation control valves, for selectively providing drip irrigation or mist irrigation in response to a control signal, and more particularly to an irrigation system having a liquid supply tube and an irrigation control valve having a valve body including an inlet port coupled to the liquid supply tube, a drip port, a mist port and a displaceable structure disposed therein, the displaceable structure being responsive to a fluid pressure for selectively directing liquid to the drip port or to the mist port.
2. Description of Related Art
In order to achieve maximum crop yield, careful monitoring and control of the growing environment must occur. For example, agricultural irrigation is used to temper climate conditions which are adverse to crop production, including watering the soil, protecting crops from frost damage, preventing the growth of mold and fungus, and applying chemicals, insecticides, pesticides and fertilizers to promote growth. These techniques are also used in animal husbandry to cool animals, such as livestock, and to provide pest control.
A variety of individual systems which provide localized climate control are known. For example, crops may be watered through surface, subsurface, sprinkler and drip irrigation systems. Surface, subsurface and sprinkler irrigation systems are inefficient means of watering since they provide moisture to the crops by irrigating the entire field area. Large quantities of water which are transported to and around the fields do not irrigate the crop directly but rather wet the entire field. A great deal of water and energy used to transport the water is wasted as a result of evaporation to the atmosphere or absorption into the soil. Thus, only a small portion of the water is actually utilized by the crop. Furthermore, the large pipelines and pumps needed to transport the vast quantities of water are expensive to purchase, construct and maintain.
Drip irrigation provides a method of continuously irrigating individual plants through small-diameter tubes and emitters. The advantage of drip systems is that water can be targeted directly at the crop to create localized high moisture areas without having to irrigate the remaining field area. The components of a drip irrigation system are much less expensive than surface, subsurface or sprinkler-type systems. As a result, drip irrigation systems are fairly common and, once installed, are efficient and fairly maintenance free. In addition, they currently are not integrated with other climate control systems. Thus, a drip irrigation system by itself may be improved in efficiency by incorporating additional functionality.
A single frost during a growing season can severely decrease or destroy crop production and yield for an entire season. Thus, frost damage protection which can be achieved through the use of smudge pots, tower fans, helicopters, sprinklers or mist irrigation is essential to ensure crop production. A smudge pot is basically a stove located in the field which burns fuel to warm the air at ground level around the crops. Numerous smudge pots are needed to warm an entire field. They are labor, fuel and maintenance intensive. The fuels may be petroleum-based which if spilled can kill the crops and pollute the environment. In addition, the combustion byproducts of the fuel create unwanted air pollution. Similarly, tower fans and helicopters are used provide air circulation around the crops thereby mixing the warmer air from above with the cooler air near the ground. Often smudge pots are used in combination with these systems to provide additional heating. But these systems are inefficient since they work globally on the fields and not locally on the crops. In addition, the capital investment for the equipment is very high.
Sprinkler systems may be used to provide frost protection for the crops, as well as for watering, since water releases heat as it freezes. The crops are watered when the temperature approaches freezing to coat the plants. The latent heat of fusion necessary to freeze water guarantees that the tissue temperatures will not drop below freezing as long as water is present on the plant. However, large quantities of water are required for this type of frost protection, and ice which accumulate on the crop may cause limb breakage. Mist irrigation, which locally increases the humidity around the corp, is another means for providing frost protection. Much like the sprinkler system, the mist irrigation system coats the plants with water to protect them from frost damage. However, by targeting water in a mist directly at the crop, much less water is need to coat the plant which reduces the amount of ice accumulation. In addition, mist irrigation also provides frost protection by transferring energy from the misted water to the air surrounding the crops. The current sprinkler and mist irrigation systems which provide frost protection cannot be targeted directly at the crops. Accordingly, excessive amounts of water or mist must be provided to ensure adequate frost damage protection.
Agricultural needs also require control over the application of chemical insecticides, pesticides, fungicides and fertilizers. Current methods of application require additional systems, such as tractor-mounted spraying mechanism or aircraft-mounted crop dusting equipment. These systems are extremely expensive to purchase and operate. In addition, they are inefficient and polluting since they result in significant overspray of the chemical into the environment surrounding the crops.
Each of the systems identified above must be individually installed, operated and periodically maintained. Thus, they are costly to purchase and operate. Accordingly, there is a need to provide an irrigation system that will perform the necessary climate control tasks of watering and fertilizing through drip irrigation, as well as, frost protection and pest control through mist irrigation. A combination drip/mist irrigation system would provide an economical system for adequately irrigating crops by reducing and conserving the water used. The system components should be simple in design, low in cost to purchase and maintain and readily adaptable to a variety of agricultural environments, including fields, orchards, greenhouses, atriums, livestock barns, etc. The individual irrigation control valves should be easy to install and appropriately align so that irrigation is targeted at the desired location. Furthermore, the irrigation system should be compatible with current irrigation technology so that it may be retrofitted into existing irrigation systems.
3. Objects of the Present Invention
It is one of the principal objects of the present invention to provide a novel irrigation control valve and irrigation system having a liquid supply tube which selectively provides drip irrigation or mist irrigation for watering, frost protection and fertilizing of crops.
Another object of the present invention is to provide an irrigation control valve whose mode of operation is controlled in response to a control signal.
A further object of the present invention is to provide an irrigation control valve which can be readily adapted to current irrigation systems for alternately providing drip irrigation and mist irrigation.
It is another object of the present invention to provide an irrigation control valve for an irrigation system capable of effectively delivering mist irrigation while reducing the total volume of water emitted.
An additional object of the present invention is to provide an easily-installed self-aligning support bracket for an irrigation control valve such that the drip irrigation is directed substantially downward and the mist irrigation is directed substantially upward.
Still another object of the invention is to provide an automated irrigation control system which monitors the environment and provides drip irrigation, mist irrigation or air circulation for providing a preferred growing environment for agriculture.